Liquid laundry starch



2,999,761 LIQUID LAUNDRY STARCH James L. Miller, Decatur, 111., assignorto A. E. Staley Manufacturing Company, Decatur, 111., a corporation ofDelaware No Drawing. Filed Feb. 20, 1959, Ser. No. 794,523 8 Claims.(Q1. 1t 6213) This invention relates, generally, to improvements andinnovations in liquid laundry starch compositions which are stabilizedand have prolonged shelf life, and which are characterized by theirfreedom from corrosive action on garments and fabrics in the presence ofmetal attachments such as metal zippers, buttons, hooks, and ornaments.

Liquid laundry starches have become increasingly popular, particularlyfor home laundry use, since starch in this form obviates the need forpreparing a starch dispersion each time starch is needed. It is, ofcourse, Well known that the ordinary starch dispersions prepared at homedo not keep well and therefore it is the practice to prepare only enoughfor immediate needs and any extra amount is usually discarded. Not onlyis this practice wasteful of the starch, but in addition there is littleuniformity in the starch dispersions prepared under home conditions.

By the designation liquid laundry starch as used herein and in theappended claims, it is intended to designate a commercial product ofhigh uniformity which is stable under ordinary conditions encountered inmerchandising, storage and transit so as to have a prolonged and goodshelf life whereby it will be and remain in excellent condition when itreaches the housewife for use by her over a substantial period of time.An ordinary solution or dispersion of starch consisting only of starchand water will not meet these rigid conditions so as to constitute aliquid laundry starch within the above designation.

Numerous addition agents have from tirne to time been incorporated inliquid laundry starches with a view of making suitable products. Ingeneral, the prior art has suggested addition of various salts,particularly common salt or sodium chloride, to impart many of thedesired properties. Major functions of these salts are to stabilize thepaste or impart resistance to cold, so that the product will resistfreezing or other undesired change during shipment and during storage inunheated Warehouses or storage rooms, and to prolong shelf life undernormal store conditions.

The stabilizing of the liquid laundry starch products is desirable, notonly from a standpoint of providing resistance to freezing and cold, butalso in inhibiting and preventing separation of the ingredients in theproduct if it is exposed to low temperatures. The liquid laundry starchproducts of this type tend, under low temperature conditions, to losetheir original homogeneous character with the result that some of theingredients may settle out or form layers. Once this occurs, it may notbe possible to re-constitute the product to its original condition, evenupon vigorous shaking or mixing.

While the electrolyte salts previously used may impart adequateresistance to these undesirable changes or developments in a liquidlaundry starch product, a troublesome effect has been traced to theincoiporation or presence of these strong electrolyte salts in liquidlaundry starch compositions. Thus, it was discovered in connection withthe making of the present invention that when clothes or garments havingmetallic zippers, ornaments, fasteners, etc., are starched with a liquidlaundry starch containing a strong electrolyte salt such as ordinarysalt, as a Winterizing or stabilizing agent, the fabrics often weakened,and were even completely eaten through.

Originally, the cause of the damage was obscure, but it was establishedthat it was due to an electro-chemical corrosive action which occurred,particularly during the conditioning, when the damp clothes were rolledup and metallic fasteners or ornaments were in intimate contact with thedamp salt-containing starch compositions. The action of the strong acidsgenerated was accentuated when brought into contact with a hot iron,resulting in the formation of many holes and scorching in the fabrics.

According to United States Patent 2,796,354, the foregoing objectionablebehavior is prevented by replacing the strong electrolyte stabilizingsalts with a mixture of borax and sodium bicarbonate. These two salts,being salts of weak acids, cannot yield corrosive acids by electrolysis.

According to the present invention, a further substantial improvement inthe stabilization and ironing properties of liquid laundry starches isobtained by using a mixture of borax and sodium tripolyphosphate as thestabilizing agent. Sodium bicarbonate catalyzes or enhances thedarkening of starch when heated to pyrolyzing temperature. Sodiumbicarbonate in a liquid laundry starch contributes to the undesirableyellowing of a starched and ironed fabric, particularly when the fabricis ironed at high temperature. This objectionable property of liquidlaundry starches containing sodium bicarbonate is eliminated by thepresent invention.

Replacement of the sodium bicarbonate with additional borax, orelimination of the bicarbonate without replacement, solves the foregoingfabric yellowing problem but creates another problem. Borax has the wellknown property of altering the viscosity and stringiness of starchpastes to which it is added. Its presence in starch pastes also causesmany of the pastes to set to a semi-rigid gelv after a moderate storageperiod atroom temperature. creasing starch and/or borax concentration.Borax is also a less eificient freeze-thaw stabilizer of starch pastesthan the strong electrolyte salts such as sodium chloride. Consequently,when using borax as the principal or sole ifreeze-thaw stabilizer, onemust compromise between its beneficial stabilizing action on one handand its deleterious gelling elfect on the other. Heretofore, the netresult of the compromise has been a sacrifice in stability. Thefreeze-thaw stability of such products can not be brought up to thesodium chloride level, for example, without leading to gelling whenborax is the sole stabilizer or to serious yellowing of the starched andironed fabric when a substantial part of the borax is replaced withsodium bicarbonate.

The new liquid laundry starch compositions conforming to the presentinvention have almost as much freezethaw stability as similar prior artcompositions stabilized with sodium chloride, but they are free of theforegoing drawbacks. The new compositions lack the objectionable gellingcharacteristic of those stabilized with borax alone, they do not lead toyellowing of the starched and ironed fabric as do those stabilized witha mixture of borax and sodium bicarbonate, and they lack the fabricdiscoloration and weakening effect of the sodium chloride stabilizedcompositions, an effect produced when the starched and dampened fabricis allowed to remain in contact with a bimetallic fastener, such as azipper, for a substantial length of time.

In addition to the borax and sodium tripolyphosphate, the new liquidlaundry starch compositions may also contain relatively minorproportions of such additives as water softeners (e.g., sodiumhexamethaphosphate), soaps, dyes, perfumes, ironing aids (e.g.,sulfonated castor oil), preservatives (e.g., phenyl mercuric acetate),and optical whitening and brightening agents.

According to the present invention, the starch co'rm The gellingtendency increases with in-' ponent of the new compositions is stablizedagainst freeze-thaw separation with about 1% to about 4% by weight,based on the finished liquid laundry starch composition, of a mixture ofborax and sodium tripolyphosphate wherein the Weight ratio of thetripolyphosphate to combined weight of borax and phosphate ranges fromabout 0.1 to about 0.5. Preferably, however, the combined Weightpercentage of the borax and sodium tripolyphosphate in the finishedproduct lies within the range of 2% to 3% and the preferred weight ratioof sodium tripolyphosphate to combined weight of borax and phosphatelies within the range of 0.10 to 0.15.

The present invention is applicable to liquid laundry starch pastes madefrom starches generally. In regard to its vegetable orig n, the starchmay come from the root, stem, or seed of a plant. Examples are com,potato, wheat, rice, tapioca, waxy maize, sorghum, sage, and waxysorghum. The starch may be raw (i.e., native) or it may be modified byone or more of the different methods well known in the art. Themodifying means include (1) the chemical type such as oxidation withhypochlorite mild hydrolysis with mineral acids, and low degree ofderivatization -(e.g., reaction with ethylene oxide to form the betahydroxyethyl ether of starch); (2) the physical type such as ballmilling and Working or kneading in differential smooth rolls (cf. U.S.Patent 2,464,081), and in extruders, (cf. US. Patent 2,214,- 018); and(3) the combined chemical and physical type exemplified bydextrinization with or Without catalysts.

Although the raw starch pastes are quite satisfactory for laundry useand, ingeneral, are more eflicient fabric stiffening agents than thecorresponding chemically modified starch pastes, the latter arepreferred for commercial manufacture and distribution. The chief reasonfor this preference is that the raw starches, by comparison with thehypochlorite oxidized starches for example, form relatively thickaqueous pastes per unit concentration of dispersed starch. As measuredby the volume of equal value diluted paste, i.e., a paste ready for usein the home laundry and having a standard index of fabric stiffeningpower, that can be made from a unit volume of concentrated paste withmaximum commercially feasible viscosity, the chemically modifiedstarches are generally superior to the corresponding raw starches.

The starch component of the new liquid compositions may also be derivedfrom pregelatinized starch products, i.e., pastes of the foregoingstarches dried and ground in such manner that the final products willredisperse in water to yield satisfactory reconstituted pastes.

Economic considerations favor the manufacture and distribution of themost concentrated paste consistent with stability and usable viscosity.There are two main considerations: (1) the cost of handling andtransporting water, which is the principal and inert component of thefinished product; and (2) the container cost per unit weight of starch.As mentioned earlier, it is in the area of such concentrated starchpastes that the present invention has particular utility. In accordancewith the-present invent-ion, the starch concentration in the finishedproduct may vary from about 5% to about 15% by weight.

, The preferred general method of preparing the new liquid laundrystarch compositions is based on the pasting or gelatinizing of anaqueous slurry of u-ngelatinized starch granules with heat. First, thestarch and water are mixed together below the starch pasting temperatureand in the finished product ratio, making proper allowances for gain orloss of Water during the heating step. Next, the well agitated slurry isheated to about 190 F. to about 210 F. This may be done by injectingsteam into the stirred slurry or by heating it indirectly with steamcoils or a steam jacket. The stirring and heating at the elevatedtemperature are continued for several minutes, preferably not less thanabout thirty, to paste the starch thoroughly. If desired, all of theoptional 4 additives except some of the commonly used perfumes andpreservatives may be added to the starch slurry prior to the pastingstep. The essential borax and sodium tripolyphosphate are withheld fromthe hot pasting stop because their presence makes the paste sufiicientlyalkaline (pH 8 to 9) to lead to air oxidation of the starch at theelevated temperature and to associated undesirable viscosity and colorchanges in the'paste. The perfumes are preferably withheld from thestarch pasting step because of their volatility, and some of thepreservatives, notably phenyl mercuric acetate, are preferably withheldbecause of their heat sensitivity. After the paste has been prepared,with or Without the permissible additives, it is cooled to about 135 F.to about 145 P. Then the borax and sodium tripolyphosphate, plus perfumeand preservative if desired, are stirred into the cooled paste.

It is desirable to finish off and package the final product at thehighest temperature which can be tolerated by the glass containers orthe product itself, Whichever is lower. Usually the latter is thecontrolling temperature. High packaging temperature alleviates theproblem of controlling subsequent spoilage of the product byfermentation.

Alternative methods of preparing the new liquid laundry starchcompositions comprise the following: (I) prepare the base starch pasteby dissolving or dispersing a suitable pregelatinized and dried starchproduct in water, then incorporate the other ingredients, including theessential borax and sodium tripolyphosphate, with or without heating themixture; (2) prepare the base starch paste by mixing the requiredproportions of ungelatinized starch and water with sodium hydroxideequivalent to the borax and sodium tripolyphosphate normally added withheating, if necessary, then add the other ingredients including theessential boric and tripolyphosphoric acids.

A preferred particular method of preparing a commercially successfulliquid laundry starch composition,

one replete with blue dye, perfume, preservative, water softener,optical whitener, and essential freeze-thaw stabilizing agents is asfollows. The ungelatinized starch is added to the required amount ofwater with agitation in a tank. If desired in the final product, thewater softener, ironing aid, optical whitener, soap, and dye are addedto the starch-water slurry at this time. The resulting mixture is thenheated with agitation to about l-210 F. with injected steam and held atthat temperature with continued stirring for about 30 minutes. The hotpaste is cooled, or allowed to cool, to F. The borax and sodiumtripolyphosphate, plus optiona1 perfume and heat-sensitive preservative,are then stirred into the cooled paste. After the latter ingredients arethoroughly dispersed and dissolved in the starch paste, the product ispackaged in glass containers.

The following examples present more detailed information aboutillustrative embodiments of the present invention.

The water, starch, sodium hexametaphosphate, sulfonated castor oil,soap, and dye are stirred together at room temperature until the Watersoluble materials are dissolved and the others are uniformly dispersed.Then the mixture is heated and stirred, without substantial loss or gainof water, at about 210 F. for about 30 minutes. Then it is cooled toabout 140 F. and the remaining ingredients in the above formulation areadded with continued agitation of the warm paste. The resultinghomogeneous product is now ready'for packaging or use.

If desired, some of the water in the aboveformulation may be withheldfrom the starch pasting operation and added later. passed through ascreen (50 mesh, for example) or centrifuged at moderate centrifugalforces to remove any solid foreign material present. The paste remainsfluid during prolonged storage and has good freeze-thaw stability.

Example 2 Grams Water 810 Starch 150 Borax 20 Sodium tn'polyphosphate 20Example 3 Grams Water 827 Starch 150 Borax 18 Sodium tripolyphosphate 3Sodium hexametaphosphate 2 The water, starch, and sodiumhexametaphosphate are stirred together cold, then heated with continuedstirring for about 30 minutes at 205-210 F. to paste the starchthoroughly. The paste is then cooled to about 145 F., at whichtemperature the borax and tripolyphosphate are added with stirring.

Example 4 Grams Water 890 Starch 100 Borax 9 Sodium tripolyphosphate 1The ingredients in the foregoing formulation are mixed and processedaccording to the procedure outlined in Example 2.

Example 5 Grams Water 900 Starch 70 Borax 20 Sodium tripolyphosphate Theforegoing ingredients are mixed and processed according to the procedureoutlined in Example 2.

Example 6 Grams Water 910 Starch 50 Borax Sodium tripolyphosphate 20 Theforegoing ingredients are mixed and processed according to the procedureoutlined in Example 2.

As used in the foregoing specification and in the following claims, theterm borax designates sodium tetraborate dodecahydrate represented bythe empirical formula Na B O .10I-I O. It is to be understood thatequivalent amounts of other forms of sodium tetraborate on Also, thefinished product may be' the anhydrous salt basis, may be substitutedfor borax in the examples and claims. One such other commericallyavailable form is the pentahydrate of sodium tetraborate, Na B 0 .5H O.The term sodium tripolyphosphate used in the foregoing specification andin the following claims designates a solid, anhydrous, Water-solubleinorganic salt represented by the empirical formula Na P O It iscommercially available under the name sodium tripolyphosphate(anhydrous). V

The term starch as used in the foregoing specification and followingclaims designates the known class of materials at a typical commercialmoisture content of about 12%. When the term refers to starch dispersedin a starch paste, as, for example, an aqueous starch paste containingfrom about 5% to about 15% thereof by weight of starch, it means 12%moisture starch, i.e., 88 parts by weight of starch drysubstanceaccompanied by 12 parts by weight of water.

Having fully described my invention, what I claim as new is:

l. A non-gelling liquid laundry starch composition consistingessentially of an aqueous starch paste containing from about 5% to about15% thereof by weight of starch, said paste being stabilized againstobjectionable separation of the dispersed starch therein, duringalternate freezing and thawing thereof, with about 1% to about 4%thereof by weight of a mixture of borax and sodium tripolyphosphate, theweight ratio of said phosphate to combined weight of borax and saidphosphate ranging from about 0.1 to about 0.5.

2. A non-gelling liquid laundry starch composition consistingessentially of an aqueous starch paste containing from about 5% to about15 thereof by weight of starch and an efiective amount of sodiumhexametaphosphate up to about 1% thereof by weight, said paste beingstabilized against objectionable separation of the starch dispersedtherein, during alternate freezing and thawing thereof, with about 1% toabout 4% thereof by weight of a mixture of borax and sodiumtripolyphosphate, the weight ratio of said phosphate to combined weightof borax and said phosphate ranging from about 0.1 to about 0.5.

3. The method of preparing a non-gelling and freezethaw stabilizedliquid laundry starch composition comprising heating an aqueous slurryof ungelatinized starch containing from about 5% to about 15% thereof byweight of starch within the temperature range of about 190 F. to about210 F. for a time ranging from about 15 to about 60 minutes, whereby thestarch is pasted, cooling the hot paste to within the temperature rangeof about F. to about F., and mixing and dissolving therein from about 1%to about 4% thereof by weight of a mixture of borax and sodiumtripolyphosphate, the weight ratio of said phosphate to combined weightof borax and said phosphate ranging from about 0.1 to about 0.5.

4. The method of preparing a non-gelling and freezethaw stabilizedliquid laundry starch composition comprising heating an aqueous slurryof ungelatinized starch containing from about 5% to about 15% thereof byweight of starch and up to about 1% thereof by weight of sodiumhexametaphosphate within the temperature range of about F. to about 210F. for a time ranging from about 15 minutes to about 60 minutes, wherebythe starch is pasted, cooling the hot paste to the temperature range ofabout 135 F. to about 145 F., and mixing and dissolving therein fromabout 1% to about 4% thereof by weight of a mixture of borax and sodiumtripolyphosphate, the weight ratio of said phosphate to combined weightof borax and said phosphate ranging from about 0.1 to about 0.5.

5. A non-gelling liquid laundry starch composition as defined in claim 1wherein the starch is hypochlorite oxidized starch.

6. A non-gelling liquid laundry starch composition as defined in claim 2wherein the starch is hypochloritc oxidized starch.

7. The method of preparing a non-gelling and freezethaw stabilizedliquid laundry starch composition as de- 5 fined in claim 3 wherein thestarch is hypochlori'te oxidized starch. V

8. The method of preparing a non-gelling and freezethaw stabilizedliquid laundry starch composition as defined in claim 4 wherein thestarch is hypochlorite 10' oxidized starch.

References Cited in the file of this patent UNITED STATES PATENTSKaufiimann et a1. July 28, 1942 Smith et a1. May 9, 1944 Becker et a1.July 15, 1947 Fuller June 18, 1957 Todd Dec. 23, 1958 FOREIGN PATENTSGreat Britain July 13, 1936

1. A NON-GELLING LIQUID LAUNDRY STARCH COMPOSITION CONSISTINGESSENTIALLY OF AN AQUEOUS STARCH PASTE CONTAINING FROM ABOUT 5% TO ABOUT15% THEREOF BY WEIGHT OF STARCH, SAID PASTE BEING STABILIZED AGAINSTOBJECTIONABLE SEPARATION OF THE DISPERSED STARCH THEREIN, DURINGALTERNATE FREEZING AND THAW THEREOF, WITH ABOUT 1% TO ABOUT 4% THEREOFBY WEIGHT OF A MIXTURE OF BORAX AND SODIUM TRIPOLYPHOSPHATE, THE WEIGHTRATIO OF SAID PHOSPHATE TO COMBINED WEIGHT OF BORAX AND SAID PHOSPHATERANGING FROM ABOUT 0.1 TO ABOUT 0.5.